Hi,
This is a clip of a test I am running using 8 LDR's, showing the ADC count.
The values are sampled once per second and an average of 10 results plotted.

It is a dull and wet day.
Note the difference in the basic LDR resistance, which is giving different ADC values.
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View attachment 361976

With this result, what would be your guess as far as the time difference from min to max resistance between LDR's?
I can set up 6 LDRs on a breadboard in conjunction with 8 LEDs and resistors. I will connect 12v and set the breadboard outside just before dusk. I will note the time the first one comes on as compared to the last. If they all come on within a 15 min span, I will measure the resistance on the third and fourth one that comes on. The average of those two will be the resistance to use for the design. Sound good?

 

Is the circuit working now with the existing code?

Absolutely!

 

Absolutely!

Then why change it?
Question, how do you know when the LDR as sensed it's dark enough to activated the PIR?

 

Then why change it?
Question, how do you know when the LDR as sensed it's dark enough to activated the PIR?

With my current circuit/PCB, for testing, I manually soldered on thru hole resistors to eliminate the chatter when the unit energized (hysteresis). Another resistor eliminated the "flash" of the high power LED when unit powered on..... etc
As far as the level of darkness needed to turn on, I tried several different variable resistors on my current board until I settled on a 15k. These tests were made in several of the units in real world conditions.

 

I'm speaking of using the LDR with the ATtiny to sense when it's dark enough.

 

I'm speaking of using the LDR with the ATtiny to sense when it's dark enough.

Oh ok. We are trying to simplify the circuit and reduce the number of components on the board. Hopefully that can be accomplished easily while eliminating the LM393 and a few resistors. If not, I will keep the LM393.

 

OK, so you are saying the code that's in the micro now is based on using the LM393?

 

hi john,
Based on the result of 8 LDR's, I would use a revised Lower Limit of 600 and an Upper Limit of 700, when using the ADC method.

The Red and Blue lines show the previous limit values
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hi john,
This is the revised plot and limit.
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hi john,
This is the revised plot and limit.
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View attachment 361988

Sorry, but I don't know how to read that as my background is structural engineering. How much time passed from the first LDR to the last? What is the time measurement along the bottom? 536...636 for example.
I do have an oscilloscope. Would that help us?
Please excuse my ignorance LOL

 

How much time passed from the first LDR to the last?

hi,
it's on the plot

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hi john,
To help you follow the plots,
By changing to those revised limits, 600 and 700 , the time between the 1st LDR and last LDR switching will be shorter and better defined.
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hi john,
To help you follow the plots,
By changing to those revised limits, 600 and 700 , the time between the 1st LDR and last LDR switching will be shorter and better defined.
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So using 8 LDRs, the first LDR reached the desired resistance at 15:57 and the last one at 16:11, so a difference of 14 minutes:seconds? seconds:hundredths? Is that military time? 3:57pm and 4:11pm?

 

OK, so you are saying the code that's in the micro now is based on using the LM393?

The code that I created and sent to Eric, which is the code I have been tweaking for several months now is for a circuit using the LM393. Eric is now trying to establish code for allowing the ATTINY to replace the duties of the LM393. Fingers crossed.

 

Still want to use the mini 360?
The 78L05 regulator rated 100ma is another sound choice.

 

Guys,
I have a supply of 10uF SMT caps. Can I use them in my circuit by any chance? (see attached schematic PDF file)

 

Still want to use the mini 360?
The 78L05 regulator rated 100ma is another sound choice.
View attachment 362018

I actually used a through hole version a while back (LM7805) and have a few dozen somewhere. I was hoping to get thoughts about that linear circuit from the others too.... whether I should just stick with the mini360 or change to the LM7805 with caps..... I don't believe I got any feedback on that question. Maybe others will chime in.... Thx!

 

The 10uf caps are fine.
The 7805 is way overkill as the mini 360 which is why I suggested the LM2936 originally but a 78L05 either surface mount or through hole will save a lot of space on the board as well.
It kind of irks me when a regulator draws more quiescent current then the load which in this case is miniscule, just saying.

 

I don't now what the latest schematic looks like but the 78L05 seems a good choice.

 

Awesome!! I will read up on the 78L05 and place it in the space taken by the mini360. Thx as always guys!! My schematic is attached in post #276.
So, can I use my 10uF caps in all cases?